Some American pork manufacturers are rethinking their use of a controversial feed additive that is banned in more than 100 countries, but not in the U.S.

Earlier this month, Tyson Foods, the largest American pork processor, announced it will prohibit ractopamine from its hogs beginning in 2020. Ractopamine increases market hogs' size, which allows producers to sell their pigs faster, but its effects are harmful to both humans and hogs, said food writer Corby Kummer on Boston Public Radio Tuesday.

"It's really dangerous and it causes crazed behavior, as if you're completely hopped up and nutty if there's too high of a human dose, and I think it's terrible for the health of the pigs too," he said. "China has banned it, the U.S. has not, and the USDA never had a good excuse for this."

Some American-owned companies are stopping their use of the additive so that they can sell pork to the Chinese market, Kummer added.

"Manufacturers need that Chinese market and swine flu is killing off half the pigs in China," he said.

Kummer is a senior editor at The Atlantic, an award-winning food writer, and a senior lecturer at the Tufts Friedman School of Nutrition and Policy.